Astelars are sleek, flat creatures with tufted wing-like appendages used for gliding through the water. Their upper surface of the semi-transparent body is covered with an array of stripes, markings, and reflective spots, some of which resemble eyes to confuse predators. Astelars change color rapidly, transitioning from blue to purple, red, or yellow, depending in the situation. Color change stems from skin cells that store pigments, regulating the release of these pigments by contracting fibers within cells.
Astelars have flippers on the undersides of their bodies, which enable graceful swimming in water and crawling or digging on land. Coloration is similar between sexes and remains the same throughout life. However, young astelars have only two small fins for swimming, and thus crawl awkwardly on land.
Astelars live primarily in marine environments off the coast of flood plains. They come ashore briefly to lay eggs on sandy beaches.
An astelar uses its strong, black beak to scrape films of microscopic organisms off the surface of aquatic vegetation. Occasionally, they will consume small calcified creatures found in the sediment.
Astelars reproduce sexually, with most females mature after one Phygarian year, but some requiring two years. Males between 2 and 3 years of age.
A male will mate with one or more females, depending on competition with other males. Males defend small territories, from which they will remove any rocks and aquatic vegetation to create a smooth sandy circle for mating. Males will remain within this circle for days, displaying flashes of color to attract females. Some evidence suggests that the size of a male’s mating circle, as well as his colorful display, determines whether a female chooses him as a mate
After fertilization, females will swim to a common nesting beach, where they will dig a nest in the sand and deposit their black, oblong eggs. A female lays 7-13 eggs, depending on her size. After a duration equivalent to 6-8 weeks on Earth, the young astelars (called pups) will hatch from the eggs and spend a few days inside the nest, relying on a sac of nutrients inside their bodies. By some mechanism still unknown, pups coordinate their movement to sea after all eggs have hatched; this mass migration presumably reduces the risk of predation for each astelar.
Each astelar has a unique pattern of markings on its body surface, such that individuals can be identified from photographs.